


All the Mistakes We Once Made

by Kittyaceres



Category: Supernatural
Genre: Alternate Universe - Canon Divergence, Angst, Canon-Typical Violence, Demon!Dean, Gen, Season 11 Spoilers, m-rated violence, nine chapters is the plan but it might be more
Language: English
Status: In-Progress
Published: 2016-03-05
Updated: 2018-02-18
Packaged: 2018-05-24 20:28:57
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 3
Words: 1,244
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6165808
Author URL: https://archiveofourown.org/users/Kittyaceres/pseuds/Kittyaceres
Summary: <blockquote class="userstuff">
              <p>There isn't anyway to remove the Mark of Cain. That's something that Dean can attest to. When Rowena removed the Mark of Cain from Dean, two things happened: the Darkness was freed and Dean's soul was split into two--one half with the Mark, the other without.<br/><br/><br/></p>
            </blockquote>





	1. Chapter 1

**Notes for the Chapter:**

> ugh apologies in advance for the spacing

“Maybe if we―”

“Maybe if you just stopped,” Dean interrupted the King of Hell, walking into the warehouse where he and the fallen Angel of the Lord were hidden out, discussing ways to get into Purgatory, for their own, selfish purposes.

It had been a long journey for Dean Winchester to end up here; allowing Cas to work with  _ Crowley _ to do anything, particularly freeing the Leviathans that had ended up killing Bobby and many, many others, was one of Dean’s biggest regrets in life. Aside from the obvious―taking the Mark of Cain, killing Death, accidentally freeing the Darkness, etc., etc. And now Dean had several advantages: he was immortal and he was here, in the past, able to undo his mistakes. And like hell he was gonna undo them.

When Rowena cast the spell to take the Mark off of Dean’s arm, it had worked―to an extent. Dean’s soul had been split into two, equal and identical copies: one without the Mark, one with. This Dean, here in this laboratory, was the unlucky half who was stuck with it. He couldn’t die, not even if he wanted to. He’d tried. He had lived through countless years on the charred remains of an earth completely ravaged by the Darkness. The upside was that because the Darkness had been freed, the Mark of Cain’s poisonous effects on him were null and void. He was, essentially, a friendly demon. And he was here now, not knowing of the force that had brought him back.

And now he stared at the unlikely pair, one of whom stared at Dean guiltily like a deer caught in the headlights. The other tried smoothly to talk his way out of this disaster: “Squirrel! What are you doing here? Last time I saw you, you were living a happy life with your girl. What was her name, Linda?”

Dean scowled at him. “Her name’s Lisa. As for what happened to me―” Dean blinked, revealing his demon eyes. “The two of you happened to me.”

Crowley’s eyebrows shot up. “Whoa.”

Castiel rushed forward. “Dean, you’re a demon? How did this happen?”

Dean backed away from him, returning his eyes to their normal color. “Once upon a time two idiots decided to break into Purgatory and accidentally nearly cause the end of the world.”

“That doesn’t answer my question, Dean.” Dean stared at Cas, deadpan.

“I’m not here to answer your questions. Please, just stop what you’re doing. I know exactly what you’re doing, and why. There is another way. _Find_ _it_. Leave Purgatory alone. _Please_.”

In the blink of an eye, Dean was gone, leaving a confused Crowley, and a conflicted Castiel.

“Well, that was something. Where were we?” Crowley asked.

Castiel shook his head. “What? You’re just going to ignore him?”

“He’s a demon! It’s not like we can exactly trust him,” Crowley shrugged.

“You’re a demon,” Castiel pointed out. “Are you saying I can’t trust you?”

“We had a deal! I always keep my end of the bargain. He, on the other hand, just came in here demanding everything for nothing! It’s a trick.”

Castiel, though, wasn’t so sure. He sensed Dean longing for him and flew off to check on him. He was both thoroughly confused and relieved to see that Dean was alive, well, and human. He didn’t reveal himself, though; he just stood there watching Dean blankly watch tv.


	2. If at first you don't succeed...

**Summary for the Chapter:**

> ...do the exact same thing and hope it works this time

**Notes for the Chapter:**

> ***SPOILER ALERT***   
> It doesn't

Several months passed before Crowley and Castiel got a warning from Dean to stop what they were doing again.

They were taking a break from trying to torture the way into Purgatory from the Alphas. It wasn’t working.

“This is a bloody waste of time!” Crowley complained.

“I’ll say. The monsters only know of one way to get to Purgatory: death. And I’m sure that’s gonna be a real help for you two.”

“Squirrel. Hello.”

“And what the hell are you two doing?”

Neither spoke.

Dean clicked his tongue. “You don’t have to tell me. I mean, obviously I already know.”

“So, there’s two Dean’s running around at the same time. How’d that happen?” Crowley asked.

“Well, you know, impending apocalypse...misguidance… I made some mistakes. Now I am eternal.”

“Eternal?”

“Yeah. I tried to eat a bullet.” Dean waved his hands down his body to emphasize how well that had worked. “I found the Colt and―” Dean mimicked shooting himself in the head. “Hell, I even stabbed myself in the chest with  _ an angel blade _ .”

“Why?” Castiel’s voice cracked as he asked.

“Everyone I care about died: Bobby, Kevin, Charlie, Claire, Garth, Jody, Sam…” Dean was tearing up. “You,” he choked out.

Crowley rolled his eyes. Castiel lurched forwards to comfort Dean but decided against it halfway. His breath was staggered as well.

Dean wet his lips. “Yeah, well… Times were tough. I had more than enough time to get over it.”

“Meaning?”

“Meaning, I was alone for thousands of years.  _ Alone, _ alone. An empty earth I called my home.” He looked at Cas: “No heaven.” He looked at Crowley, who was looking slightly excited: “And no hell. No Purgatory, even!”

Crowley and Castiel looked at him confused, at each other, and then back at him. Castiel took another half-step forwards. “How did this happen?”

“It’s just a downward spiral that starts here, Cas.” Dean took a couple steps towards Castiel until they were inches apart from each other. He cupped Castiel’s face: “Please, please stop what you’re doing. I’m fucking serious, Cas. Don’t let that future― _ my future _ ―happen. We can find another way to deal with the war in heaven. Please, there’s another way. Let’s find it. Or just don’t do anything at all. I know what you plan to do. Is it right? I’ve been down the path of slaughter, and it’s not fun. It’s hard to live with yourself afterwards. You won’t want this. I don’t want this for you.”

Castiel’s breath hitched. “Dean…”

“I’m begging you here. Please, Cas.”

Dean thought about what he’d gone through, and judging by Castiel’s growing despair, he figured that the angel was reading his mind. “Let’s go…” he whispered. Castiel nodded.

“Whoa, whoa, wait. All it’s gonna take is for Dean here to bat his eyelashes and you do whatever he says?  _ You’re so whipped, _ ” he said.

Castiel looked at Crowley, considering what he’d said. Dean pulled Cas’s face back towards him. “Cas?”

Cas didn’t know what to do or whom to listen to, so he disappeared.

“You’ve hurt his feelings,” Crowley said.

Dean rolled his eyes at Crowley. “You bastard,” he muttered. Then, louder, he continued, “You think that Cas is the only one who’s gonna get screwed over here, just because he’s the only one I’m warning? Bullshit! He’s just the only one of you two that I care about. You should realize, though, what you guys are planning, it’s not gonna end well. You’re gonna get screwed over. We’re not the only ones Cas is gonna betray.” With that, he disappeared. Crowley shrugged.

.

**Notes for the Chapter:**

> and in the next chapter...  
> THE BOYS FIGHT
> 
> Stay tuned!! :)


	4. Author's Note

So... uh it's been like 2 whole years since I even wrote this story, and I did have a plan to finish it, but I kind of forgot and moved on to other stuff...and I don't even know if I have the document on my computer anymore because I got a new one since then, but if you want to read until I left off, there's like seven chapters more on Fanfiction.net so...

[Fanfiction.net link](https://www.fanfiction.net/s/11627517/1/All-the-Mistakes-We-Once-Made)


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